Use of precast grid deck supports staged construction and accelerates superstructure replacement

Bridges Case Studies October 23, 2015
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Interstate 81 is a vital trucking route along the Appalachian corridor and in particular, south central Pennsylvania. Years of heavy traffic and the harsh Northeast weather abused the parallel bridges spanning Leitersburg Road near Greencastle.

 

The conventional concrete bridge decks and steel girders on both the northbound and southbound bridges were in poor condition and needed to be replaced. Without any economical detours available, one of the main challenges the Pennsylvania Department of Transportation (PennDOT) faced was how to rehabilitate the structures and maintain both lanes of traffic in each direction throughout peak traffic times. 

 

The resulting solution was an aggressive rehabilitation project that would replace the superstructures with nearly 10,000 sq ft of bridge deck in four stages and within a 48-day timeframe. The $3.9 million accelerated construction contract was awarded to Cottle’s Asphalt Maintenance Inc., a local Pennsylvania contractor headquartered in Everett only an hour away from the project site.

 

Accelerated staging on the project separated the work into four half-width bridge closures, with a crossover redirecting one lane of traffic from the bridge under construction onto the opposite bound.  Each stage required removing and replacing the bearings, girders and deck, along with as-needed abutment and bearing seat repair.  PennDOT required all four lanes of traffic maintained throughout the day, but permitted the contractor a full bridge closure from 9 p.m. to 6 a.m. each night with only three lanes of traffic open. During the full closures the contractor was able to remove and set the new girders, as well as make the closure pours in the precast grid reinforced concrete deck panels.

 

A key component allowing the short construction turnarounds was the precast steel grid reinforced concrete deck panels, supplied by BGFMA member fabricator L.B. Foster Company.  Cottle’s Asphalt Maintenance handled the precasting with their own prevailing wage forces, which saved them significant time and money over using a local precast yard.  The precast deck panels were installed in less than a day for each stage and the concrete closure pours reached 4,000 psi in less than 20 hours, which allowed the contractor to put equipment on the bridge to install the cast-in-place parapets the day following the closure pours.

 

The project kicked off on Aug. 5, 2015 and was completed before the first day of fall, seven days ahead of the permitted schedule. According to Mike Cottle, president, “There was only a short learning curve to place the precast grid deck panels and closure pours, so installation ended up going quicker than anticipated. The precast grid deck played a large role in the success of keeping the project ahead of schedule.  I expect the durable steel grid deck to stand up well to the heavy truck pounding that I-81 sees.”

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